can contribute
Regular verb: contribute - contributed- contributed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can contribute
you can contribute
she can contribute
we can contribute
you can contribute
they can contribute 	I can be contributing
you can be contributing
she can be contributing
we can be contributing
you can be contributing
they can be contributing	I can have contributed
you can have contributed
she can have contributed
we can have contributed
you can have contributed
they can have contributed	I can have been contributing
you can have been contributing
she can have been contributing
we can have been contributing
you can have been contributing
they can have been contributing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't contribute
you can't contribute
she can't contribute
we can't contribute
you can't contribute
they can't contribute 	I can't be contributing
you can't be contributing
she can't be contributing
we can't be contributing
you can't be contributing
they can't be contributing	I can't have contributed
you can't have contributed
she can't have contributed
we can't have contributed
you can't have contributed
they can't have contributed	I can't have been contributing
you can't have been contributing
she can't have been contributing
we can't have been contributing
you can't have been contributing
they can't have been contributing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I contribute?
can you contribute?
can she contribute?
can we contribute?
can you contribute?
can they contribute? 	can I be contributing?
can you be contributing?
can she be contributing?
can we be contributing?
can you be contributing?
can they be contributing? 	can I have contributed?
can you have contributed?
can she have contributed?
can we have contributed?
can you have contributed?
can they have contributed? 	can I have been contributing?
can you have been contributing?
can she have been contributing?
can we have been contributing?
can you have been contributing?
can they have been contributing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I contribute?
can't you contribute?
can't she contribute?
can't we contribute?
can't you contribute?
can't they contribute? 	can't I be contributing?
can't you be contributing?
can't she be contributing?
can't we be contributing?
can't you be contributing?
can't they be contributing? 	can't I have contributed?
can't you have contributed?
can't she have contributed?
can't we have contributed?
can't you have contributed?
can't they have contributed? 	can't I have been contributing?
can't you have been contributing?
can't she have been contributing?
can't we have been contributing?
can't you have been contributing?
can't they have been contributing?